Previous results from this laboratory demonstrate that T cells are markedly sensitive to modulation by cannabinoids as evidenced by altered interleukin-2 (IL-2) gene expression. Our results suggest that the molecular mechanism for IL-2 modulation by cannabinoids is complex and involves multiple signaling cascades whose modulation is both cannabinoid receptor-dependent and -independent. The following key observations support this premise: (a) cannabinoid-treatment induced a marked, sustained and concentration dependent elevation in intracellular ([Ca+2]i) that was attenuated by cannabinoid receptor antagonists; (b) concordant with elevated [Ca+ cannabinoid treatment disrupted the activity of the downstream effectors, NF-AT, AP-1, ERK MAP kinases and calcium/calmodulin-dependent kinase, CaM KII; and (c) cannabinoid treatment induced rapid nuclear translocation and DNA binding of glucocorticoid receptors (GR). Based on these and other findings, the overall goal of this five year research plan is to test the Hypothesis: Cannabinoid-induced inhibition of T cell activation, as assessed by IL-2 gene expression, is mediated concomitantly through cannabinoid receptor-dependent and -independent mechanisms involving sustained intracellular calcium elevation and activation of glucocorticoid receptors, respectively. Our hypothesis will be test using four specific aims (SA). In SA#1, we will characterize cannabinoid-mediated [Ca+ elevation and the role of CB 1 and/or CB2; In SA#2 we will characterize the activation of CaM KII by cannabinoid- mediated enhancement in [Ca2]. In SA#3 we will characterize the downstream consequences of cannabinoid-mediated enhanced of [Ca2] and CaM KII activation on IL-2 regulation. Lastly, in SA#4 we will characterize the role of cannabinoid-mediated GR activation in T cell dysfunction. The significance of the results from these studies is that they will provide important new insights into the molecular mechanism(s) responsible for cannabinoid-mediated immune suppression.